Technical Field
Certain embodiments of the present invention relate to a shovel which includes a swiveling electric motor and a power storage system.
Description of Related Art
In the related art, a hybrid construction machine is known, which includes a generator and a hydraulic pump which are driven by an engine, a swiveling electric motor which is driven by power generated by the generator, and a hydraulic actuator which is driven by the hydraulic pump. In the hybrid construction machine, in a case where the hydraulic actuator and the swiveling electric motor are simultaneously operated, the hydraulic actuator is driven by the hydraulic pump, and the swiveling electric motor is driven by power generated by the generator. In addition, when the power consumed by the swiveling electric motor is not covered by just the power generated by the generator, power which is accumulated in an electric double-layer capacitor is used. Moreover, when the power consumed by the swiveling electric motor is not covered by the power generated by the generator and the power which can be discharged from the electric double-layer capacitor, the output of the swiveling electric motor is suppressed. The reasons why the suppression is performed are because torque supplied to the hydraulic pump decreases and the speed of the hydraulic actuator decreases in a case where the power generated by the generator increases, and adverse influences of a decrease in the speed of the hydraulic actuator with respect to an operation feeling are greater than adverse influences of a decrease in swivel speed with respect to the operation feeling.